Wednesday, December 29, 2004
... /////

In response to a question (about the recent status of Hawking's 2004 claims) from David Goss, let us start with some well-known history. Hawking was the first person who in 1974 successfully merged (even though just approximately, in what we call the "semiclassical approximation") the laws of general relativity with the laws of quantum field theory to derive a nontrivial quantitative result - namely the Hawking radiation, including its spectrum. Via thermodynamics, it can be also used to derive the black hole entropy.

Hawking's framework to calculate and his insights are beautiful. Many theoretical physicists believe that he deserves a Nobel prize, and we're just unlucky that there are not too many small, radiating black holes around. In one of the unlikely scenarios of "low energy gravity", the LHC could be producing small, radiating black holes - which would be a terrific news for Hawking. But there also exists a confirmation that is the second most convincing one after the experiments: his calculation of the Bekenstein-Hawking entropy has been confirmed by string theory, for very many different non-trivial examples of black holes.

Hawking's and similar calculations have one unpleasant aspect only: they also seem to imply that the initial matter, forming the black hole, is evolving into a mixed thermal state (the radiation that remains after the black hole evaporates) which is completely universal and only depends on some "major" observables describing the initial state such as the total charge and total mass. All the details of the initial state are lost.

Tuesday, December 28, 2004
... /////

I don't know what about you, but my policy is to count the total price of the goods that I buy in the shops - with the error not exceeding 3 percent.

I just returned from my usual shopping in the Massachusetts Shaw's Supersymmetric Market (MSSM). The cashier had some problems to scan the barcode of the two DANNON (for fellow Europeans: DANONE) yoghurts with fruit at the bottom. Incidentally, do you know that yoghurt with added fruit marmelade was invented in Prague in 1933, originally to protect yoghurt from decay?

OK, so she tried to scan the barcode, on her "PC". And it was like beep beep beep beep beep beep. And then she said "40 dollars". Half of that amount was true. And I was like Huh? It devoured my money. It was a very good amount of money.

Because of the counting policy, I did not have to look confused anymore and trust the "expert". Instead, I could have immediately said

That's nonsense. This is a $21.30 shopping.

And she had to count it again and she had to do it fast, so the total amount wasn't as good for her: $21.57. It's kind of ... a bummer.

I'm not Ellen Feiss, and I'm not a student, but this story is true! Of course, her error is that she counted the yoghurt 23 times. :-)

Petra Němcová survives tsunami

Petra is not only my countrymate, but she has also a very similar profession. Many of us study supersymmetric models, and she's a supermodel herself! I believe that her story is, so far, the most scary but especially most captivating among the stories of all people from the West who had to become witnesses of the very sad event in Asia that killed roughly 100,000 people. She had to grab a palm, while her pelvis was broken, and hold it for eight hours, while she listened to the screaming children that suddenly became quiet - and she had to watch her boyfriend, the British photographer Simon Atlee, who was dragged away by the stream and who is still missing. See the other articles here.

Did Earth's rotation become faster?

As Sean Carroll pointed out, some people believe that a large earthquake may speed up the frequency of Earth's rotation - i.e. shorten the day. Correct me if I'm wrong, but the explanation is that the size of Earth shrinks a little bit - it rearranges its mass in a more compact form - which reduces its moment of inertia. Because the angular momentum is kind of conserved, the angular frequency must increase. Am I right? A calculation leads to an estimate that can possibly be as large as 3 microseconds. Do you believe it? This change would not be measurable 40 years ago, but today the accuracy is 100 times better. Does it seem like a lot to you? Well, you still need 300,000 days i.e. roughly 1000 years to be allowed to remove one leap second; or add one? I'm not sure right now.

It's also estimated that some islands were moved by as much as 20 meters.

Sunday, December 26, 2004
... /////

In the morning, 25 years before the asteroid was supposed to land, I had to ask: which bike is mine and which of the bins is for 1 PETE containers? :-) Incidentally, this story is dead because the impact probability dropped to 10^-5 in the afternoon of December 27th, 2004 - as was expected - but nevertheless it may still be fun to read how the story looked before it disappeared. The text below is obsolete, but have fun:

The probability than an asteroid named 2004 MN4 of around 390 meters (previously reported as 440 and then 380 meters) will hit Earth is estimated to be around 2.7 percent right now. It carries the number 4 on the Torino scale - clearly the highest rating of all such objects ever observed because no previous object has ever been above 1! However, there is still a 97% likelihood that the estimated probability will start to decrease soon, as the observations become more accurate; in fact, the probability has already reached 2.4 percent, then dropped to 2.2 percent, before jumping to 2.7 percent. However, it may also continue to grow...

I hope that you're not superstitious because the possible colission will take place on Friday, April 13th, 2029. According to my calculations, it could occur at 9:07 pm (Universal Time), and this is enough for you to figure out which place on Earth will it roughly land at.

We may want to produce some more nukes and make them ready for the unexpected application - splitting such an asteroid into pieces. Actually in the case that the probability won't decrease below 1 percent in 4 months, or if the Torino classification jumps above 4 (to the orange or red zone), I would endorse an immediate action - just send a couple of H-bombs to that asteroid and break it in two halves - even if it were just a training. If it does not work, we must send a better mission that will drill a hole in it and put H-bombs in the hole. The earlier you deflect such a thing, the cheaper it is. According to an Australian "astronomy educator", if an asteroid is made of stone, it will mostly evaporate in the atmosphere. Most of the commentators on this blog however agreed that the atmosphere is clearly unable to destroy an asteroid as large as 2004 MN4. So the impact won't be too different as the impact of an iron type asteroid whose colission would be equivalent to 100 Hydrogen bombs - over one thousand of megatons of TNT.

The Earthquake in Southeastern Asia is, first of all, a sad event for the people there, and it is sad for all of us. Tens of thousands of lives were suddenly ended by evil, despicable acts of mother Nature.

The earthquake (8.9) was the strongest one since the 1964 tremor in Alaska, and the fifth strongest in the last 100 years. (Note that the average period is 20 years, so we've had a rather long period between two large earthquakes.) It came exactly 1 year after the quake that destroyed the Iranian city of Bam. Because the center of the earthquake was just below the surface of the ocean, it generated massive waves, the tsunamis. Well, some other sources claim that it was 10 kilometers below the sea level, but there are many other contradicting news, too.

I always wondered whether it's possible to escape from these tsunamis. But it's not realistic. The waves on the ocean have very different dispersion relations from the electromagnetic waves, for example. More precisely, the speed increases with the size of the waves. (Well, it's not just about the dispersion relations because the waves behave non-linearly as a function of their amplitude.) The ideal approximation of tsunami is the so-called "shallow-water wave" in which the speed is sqrt(g.d) where d is the water depth.

It just happens that these waves that can be as high as 10 meters propagate with the speed about 300 miles per hour - something like 120 meters per second. Now if you're enjoying the Sun on the beach, you only see the wave when it's one mile away or so, and therefore you have something like 10 seconds to run. It's very hard to run in the sand, so perhaps it's better to give up immediately. You just can't escape from a wave which is 10 meters in height unless you are a highly intelligent squirrel that can quickly climb a sufficiently massive tree or unless you see a staircase nearby. Well, what I just wrote is not quite true because the waves usually slow down to about 30 miles per hour when they approach the land, because of the dependence on the water depth mentioned previously, and therefore you can actually have a minute to leave...

There are also some warning systems (one still has a few hours before the wave reaches the shores), but unfortunately they were not used in this case: tsunami are not too frequent in this are and the people are too poor to organize some high-tech security systems. Tsunami means "wave in port" or "harbor wave" in Japanese.

No news are often good news. Usually we don't write about them. Let's make an exception.

The LHC should be finished in 2007, and right now it seems very realistic. (This good news contrasts with the Tevatron that was recently stopped for quite some time.) The British have finished the first of four barrels that will form the core of the SCT (SemiConductor Tracker) - see a very informative article at

The LHC needs a new computing grid: it will create 10 petabytes of data every year. If you don't know what a petabyte is, you may like the translation of BBC: 10 million CDs of data per year. ;-) Also, the Fermilab and the Berkeley labs announced that a key U.S. component for the LHC has been completed:

I am amazed by the comparison of the quality of Will's text and the text of the evangelists. Most of the evangelists are being demonstrably paid as global climate "experts". However, in the two articles of comparable length, these nine "scientists" are only able to collect a couple of insults, while Will offers a plenty of rational arguments with detailed references.

Will describes Crichton's book and its main story: the environmentalists' lawyers suddenly find out that the theory was a lie, so they must manufacture artificial tsunamis, floods, and other disasters. Will compares Crichton's book to other books, and says a couple of words about the political background and why the "red states" are more likely to enjoy the book. His language sounds good and there are several "powerful" sentences such as

Crichton's villains are environmental hysterics who are innocent of information but overflowing with certitudes and moral vanity.

The nine evangelists were only able to copy the second part of this sentence and use it against Will himself. Unimpressive.

But it is even more obvious if one compares how Will vs. the nine evangelists discuss some more particular topics, for example the observed decrease of the temperature at various places. Will (with Crichton) explains that the skeptics have identified that glaciers in Iceland have been advancing and Antarctica is cooling down. The evangelists only reply with a manufactured criticism that Will is certainly doing an "elementary error" because he would definitely think that if a stock in his portfolio goes down, the whole portfolio must be losing its value. Unimpressive.

The global climate expresses the "average" of all places in the world, and it is scientifically unacceptable to humiliate one piece of data and pretend that it is less important than other pieces of data. Some places are cooling down, and some places are warming up. The number of places in one group may be different from the number of places in the other group - Nature never guarantees an exact democracy - but that's certainly far from being the reason to reduce the annual growth of the world economy by one percent or even more. The very question of the trend of temperatures in the Americas is very subtle. The people at RealClimate.ORG will never publish an article that South Texas sees the first white Christmas in 86 years this year. They know what's their goal, and they know which data they must throw away to achieve their goal.

Back to Will.

Will quotes Fiona Harvey, the Financial Times's environmental correspondent, who explains that climate predictions are much like financial forecasts but they involve many more variables. I think this is an excellent analogy. If you look at the actual forecasts in the financial world, you will see how unreliable they are. The climate may be even more complex. The evangelists have nothing to say about either of these things. Instead, they quote three favorite bureaucratic bodies - obviously containing scientists with comparable political bias as themselves - that stated that the global warming probably exists and probably has human-induced components.

But the most striking comparison of the two articles is the discussion of the evolution of a fashionable panic. Will's text especially talks about the global cooling believed in the 1970s, and it's incredible how little these nine evangelists seem to know about the history of "their" field and probably not just the history. The nine evangelists only say that Will is wrong and they may explain it sometime in the future. On the other hand, Will wastes no time and presents a lot of explicit sources that show how real the global cooling panic was, for example:

The New York Times (Aug. 14, 1975) reported "many signs" that "Earth may be heading for another ice age."

The Christian Science Monitor reported (Aug. 27, 1974) that Nebraska's armadillos were retreating south from the cooling.

My readers already know that I think that the threats that the climate is heading to a disastrous warming are products of junk science and organized brainwashing, and therefore it's not the main point that I find worrisome about these debates. The most worrisome thing is how many junk scientists are actually being paid as scientists, even though nine of them are obviously less able to construct a rational argument, article or a paper than a single journalist. They should be ashamed and they should be fired.

Update: RealClimate.ORG has also published a more detailed attempt to debunk George Will. This more detailed version is a little bit more meaningful, but it still seems to me less meaningful than Will's text.

Friday, December 24, 2004
... /////

This text follows my discussions with Nima Arkani-Hamed and David Goss.

Some people don't like the fact that the arguments in string theory are increasingly theoretical in nature, and that our theories seem to give us less exactly calculable sharp predictions that are verified experimentally.

However: it's not just string theory: the whole particle physics has been becoming increasingly theoretical and string theory just continues in the same direction. What do I mean?

QED, Electroweak theory, QCD: increasing groups, decreasing accuracy

The peak of the old-fashioned quantitative predictivity of very particular facts in physics was QED which stands for Quantum Electrodynamics. You know that people could have calculated its predictions already 50 years ago, including the quantum loop corrections, even though they did not quite understand why their methods were working (The Renormalization Group), and the most precise predictions - like the anomalous magnetic moment of the electron - have been successfully tested with the accuracy of 13 decimal places!

Thursday, December 23, 2004
... /////

OK, some news related to the issue of climate variability. (It may be a better term than "climate change" because "climate change" already includes some sort of answer including a revolutionary "change" and is therefore biased.)

Michael Crichton's thriller State of Fear may be a book of non-fiction after all. Do you remember the eco-terrorist organization NERF that took over the region? The organization based on the lies about the global climate that was promoting their interests using the mafia techniques? So this NERF already have their own blog in the real world, and their goal is nothing less than to "change the way how journalism discusses questions of the global climate". Given the fact that the ratio of the catastrophic sensational newspapers articles to the reasonable science-based articles about the global climate is roughly 5:1 already today, and NERF clearly wants to increase this ratio further, we're not far from Crichton's novel. The website I talk about is

Among its nine authors we find William Connolley, my friend ;-) from Wikipedia who is kind of twisting all wikipages about the global climate, as well as Michael Mann a Ray Bradley, two of the co-authors of the largerly abandoned paper about the "hockey stick graph" which was based on a rather poor manipulation with the tools of statistics.

George Bush became the Time magazine's "Person of the year 2004" for the second time. Edward Witten has made it to the top 100 of the most influential people. Congratulations. Incidentally, I was voting for the most worrisome article about string theory in 2004, and the winner is the article in the Time magazine.

The first book in 2004 that has left an enriching impression and triggered the imagination of the president of India APJ Abdul Kalam, apparently a sibbling of Steven Weinberg :-), was the new excellent book "The Fabric of the Cosmos" by Brian Greene. Mr. President quite often refers to this book, but I am a bit confused whether he read the same book because he believes that Brian Greene "reconciles" string theory with loop quantum gravity! ;-)

String theory affects not only mathematics, but also art - especially Stephen Linsteadt's oil, oil pastel and graphite expressionistic works based on String Theory :-)

Santa Claus may be a threat to the environment because of his ion shields, trips between the dimensions, and the air friction, as new physics research shows. A problem with that paper may be that they used bosonic string theory and identified Santa Claus with Einstein himself.

Chen Ning Yang whom we usually associate with Robert Mills decided to learn mirror symmetry. Why exactly mirror symmetry? Because he's 82 while his new wife is 28.

Sunday, December 19, 2004
... /////

This particular article is about fuel that may be produced as cheaply as for 15 dollars a barrel - from organic waste such as turkey guts. And it seems to be environmentally friendly - well, pollution created from burning the fuel has always been the most serious challenge of similar approaches. The technology seems to mimic the actual processes that led to the natural creation of fuel. You may read more about this possibility here:

This article appeared a year ago, and therefore they still presented the price as being 10 dollars a barrel. It seems that the factory in Carthage, Missouri, is now running at 80 percent of its capacity, as you can see if you read the interview with Brian Appel, its CEO and a skillful manager who seems to know what he's doing:

Appel expects the new plants, which should also produce diesel fuel for powerplants in 15-20 minutes, to process the beef. They are working on a variation of the technology that could be used in the cars; this also requires a modification of the motors, something that the Big Three works on, too.

The people who blame the US for producing more CO2 than others - and who want to "punish" the US by the Kyoto-like protocols and similar anti-growth bureaucratic regulations - don't realize (or perhaps don't want to realize) that it is the same United States that is the most likely place where the new technologies will be (and already are being) discovered and realized in practice.

Snow returned to Cambridge, and that's a good opportunity for another article about the global warming.

Michael Crichton seems to be a rather impressive person. With his almost seven feet, he was a rising basketball star. More importantly, he graduated from Harvard University (his field was anthropology) and then he studied medicine, before he became a bestselling author of thrillers.

A couple of years ago, he believed that the global climate may be visibly influenced by human activity. He decided to study these questions in detail. The result is that he figured out that most of the global warming hysteria is based on shaky and politically flavored science.

The global warming science today is not really run by truly honest scientists, but more typically by "concerned scientists" who are so concerned that they prefer to present a particular type of results only because it makes the public think in a direction that is better for their funding and for the political power of their friends who are almost always left-wing. This "concerned", "improved" attitude to science is usually expressed by the Schneider doctrine:

We have to offer up scary scenarios, make simplified, dramatic statements, and make little mention of any doubts we may have. Each of us has to decide what the right balance is between being effective and being honest.

This statement about the global climate science from the infamous Dr. Schneider was taken out of context, but let's hope that I am not the only one who thinks that for a scientist, it is unacceptable in any context.

Incidentally, I am always amazed that they use the name "concerned scientists" themselves because to me it sounds as a synonym of "biased scientist", "scientist with an agenda" or a "pseudo-scientist". But it may be just my personal feeling - a feeling of a person brought up in a socialist country - a country where the "best" scientists, artists, and people in general were supposed by the Communist Party to be "concerned" (for Czech speakers: I really mean the adjective "uvedomely").

If you want to create a movie or write a book about the weird catastrophic scenarios proposed by the global warming proponents, it's not so difficult. You shoot a scientific nonsense like The Day After Tomorrow with a lot of visual effects. It's fun to watch these scenes. Moreover, people with the scientific credibility comparable to Al Gore and his likes are always ready to say that your absurd movie is just a slightly exaggerated, but true portrait of reality - and they will thank you for pointing out what is going to happen.

On the other hand, the idea that the global warming theory is a result of poor science and the influence of sensational journalists does not seem to be a good starting point to write a catchy book. If the global warming theory is a bubble, there is nothing shocking or sensational that one can show in his book or movie, you might think.

Well, this is exactly where Crichton started, and his State of Fear is now the #4 (it was #2) on the amazon.com's bestseller list. How can it be?

Of course that his story about the eco-terrorists is relatively unlikely to be viewed as the most exciting fiction written by Crichton. What helps Crichton is that his story resembles the real world a bit. Well, not quite. The eco-terrorists in Crichton's book take over by using high-tech know-how, deep-diving submarines, hypersonic cavity generators etc. which is yet to happen in the real world. ;-)

The main character is Michael Evans, a lawyer from L.A. He works for a millionaire and philantropist George Morton (note that he's not really called George Soros or anything like that) who financially supports NERF, an environmental group that sues the US on behalf of an island that was supposed to be damaged by the increased sea level.

Evans is being educated (or brainwashed) by both sides: by the dark side of the environmentalists paid by Morton, as well as by a truly positive character, Prof. John Kenner from MIT (although he could have been called Richard Lindzen, too). Hundreds of pages in the book include a very unusual type of story for a thriller: graphs related to the global climate.

Kenner (and Crichton) actually present a lot of very relevant information about the global warming. How many people know, for example, that Antarctica is cooling down? The Antarctic ice sheet is expected to grow in this century, too. You will never read about this in the newspapers; instead, you will be offered 496 articles about Joe the Arctic Polar Bear who may probably prefer if the average temperature were 1 degree lower in the next century, so it may be useful if the humans paid 4 trillion dollars to make Joe happier.

That's of course too cool and one is naturally skeptical. I am doubly skeptical because New Scientist has not been a terribly serious journal in my eyes in the last 5 years. Nevertheless I think it's fun to bring your attention to this article because observing a string in the telescope is the favorite scenario of many leaders of our field how string theory should eventually be proved. ;-)

OK, let me now pretend that I believe this stuff. The cosmic superstrings were recently studied - and "predicted" :-) - by Joe Polchinski et al., see his following papers

and their citations and references. The paper explains how the cosmic superstrings can be distinguished from other, more ordinary types of cosmic strings. (The article in New Scientist only dedicates the last paragraph to the difference between the fundamental strings and other types of cosmic strings.)

Tuesday, December 14, 2004
... /////

Tom argues that the landscape is not a well-established feature of string theory. In a conceptual paper which does not bother you with too many equations (the Wheeler-DeWitt equation being an exception), he argues that

one must distinguish the 1PI and the Wilsonian effective actions more carefully: the 1PI action describes the whole field content, and you get the same action regardless of the point around which you expand

on the other hand, the Wilsonian effective action contains the low-energy degrees of freedom that depend on the point in the configuration space - and this is the type of the effective action that one obtains in string theory

Tom re-uses his statements that one cannot think about the bubble of another vacuum (such as a de Sitter bubble) as an excitation of the original vacuum, and interprets the Guth-Farhi results in this fashion - one cannot verify the existence of a dS bubble inside the bottle because the external observer sees that it is surrounded by a black hole

If I understand well, Tom does not propose new arguments that the numerous KKLT-like vacua don't exist. Instead, he says that they cannot be effectively used as vacua of the same theory, i.e. they cannot be combined into a big multiverse, and therefore there is no cosmological mechanism that would connect them and create a realistic ensemble of the Universes.

Monday, December 13, 2004
... /////

They claim that the hypothesis about Viktor Yushchenko, the West-leaning presidential candidate in Ukraine (the situation has already been discussed here), who has been poisoned by dioxins, is now "rock solid". The concentration of dioxins in his blood is 1000 times larger than normal (actually 6000 times, according to the Financial Times)!

You know, dioxins are never healthy - they always represent a risk of cancer as well as other illnesses. In the Czech Republic, we know the word "dioxin" in relation with a chemical company called Spolana Neratovice that has been blamed for emitting more dioxins to the environment than what would be appropriate - and 80 people in the period 1964-68 became victims and suffered from similar problems as Yushchenko. (Spolana was producing something that, paradoxically and through various contracts, was used by the U.S. army in Vietnam as Agent Orange.) However, I am sure today even Greenpeace would not claim that the concentration of dioxins in the blood of citizens near Spolana is larger than the normal limits by three orders of magnitude! The situation improved drastically since the 1960s although it's not perfect yet.

Assuming the most obvious explanation for the large concentrations of dioxins in Yushchenko's blood, this event really looks like a horror story from the old Stalinist times - although the main open question remains "who did it?". Such things have been unfortunately common in the former Soviet Union, see e.g. the examples here:

Sunday, December 12, 2004
... /////

This is just a small addition to the comments about the hedge funds and short selling.

There exists an incredible anti-capitalist financial terrorist and moron, a 44-year-old former Wall Street broker called Max Keiser who decided, together with Zac Goldsmith, a journalist from "The Ecologist" and a son of a more famous father, to destroy the Coca Cola corporation by short-selling its stocks.

He blames Coca Cola for containing sugar, for using its own logo, for violations of the human rights in Colombia, for poisoning land in India, for racism, and so forth. Keiser's brain simply seems a bit damaged, to say the least.

Saturday, December 11, 2004
... /////

There has not been an article on this blog focusing on economy yet, I think.

The American "twin deficits" have become a popular topic - especially on the currency markets. Every time a new journalist learns something about the basic flows of money in the economy, he or she writes an article. This article is read by other journalists who write their own articles, and so forth. Consequently, there are thousands of articles about the American deficits and all of them look alike.

Don't get me wrong: I think that the US trade gap shows that something is not quite right. It's great that the Americans like almost all other nations in the world, and they buy all of their products - but they're just doing too much of it and others are doing too little of it! :-) The British empire in the 19th century was not only a superpower, but also the world's biggest creditor. (Note that it did not help them too much to remain the number one superpower either.) The budget deficit is also kind of wrong - although this one is more likely to shrink if the economy works well. After 1999, I did not believe for a single minute that the US budget surplus would be a permanent state of affairs and one should "plan how to spend it" - in other words, I believed that it should have been spent to compensate a part of the debt from the previous years and the following years. Yes, of course that I would have also supported tax cuts, but they should come together with cuts in spending.

Although the deficits are not right, my feeling is that some not-terribly-deep ideas are repeated too many times. Also, some unfounded rumors - such as the statement "China is reducing its US dollar reserves" - appear all the time - this one has been officially denied. So let me propose a provoking alternative description of the situation.

The sino-dollar zone

The USA effectively have a monetary union with China because the Chinese government pegs their yuan to the US dollar. The monthly trade gap of the Sino-American union is roughly 40 billion dollars: 50 billion of the US gap and 10 billion of the Chinese surplus: these two numbers also include the internal trade between China and the USA. The deficit is roughly 25 dollars per capita; obviously, the Chinese citizens are treated as people with all of their human rights!

Let me call the monetary union "USAC" - which stands for The United States of America and China. ;-) It's a disconnected country with 50 states on one continent and another, large independent state on another continent which is run by a Communist Party. It has two capitals and nearly 1.6 billion people.

Those 25 dollars of the monthly trade gap per a citizen of USAC is a lot, but it is not so much if compared to other countries. For example, Australia's October trade gap was nearly 2 billion US dollars, which is 100 dollars per capita.

United Kingdom's October trade gap was 8 billion USD, which is 130 USD per capita. Note that even if I split USAC to America and China, the US gap will be "just" 170 USD per capita (about 6 dollars a day) - it's not so terribly different from the UK, and you may explain the difference by a better ability of the USA to grow. The more space & population growth a country has, the more you should expect that it will attract investments to support its growth. It's of course incorrect to imagine that the only sustainable configuration is when all trade deficits vanish.

Why I talk about America and China together? Because every time the dollar loses a cent, the yuan loses, too - which makes China even more competitive. Most people don't appreciate the fact that the depreciating dollar has also depreciated the yuan.

Imagine that yuan becomes a floating currency. Free market is always great, but will it be enough to restore balance in the global trade? I am not so sure. Even if China's currency would double, China would remain an excellent source of cheap labor simply because the salary per hour is just 10% of the salary in America, for example.

(Some people say that the yuan is only undervalued by 40 percent - I don't believe it. The correction would start with 40 percent, but it would continue.)

Although a floating Chinese currency is eventually desirable, it may be inappropriate to make this change in the period when many people believe exaggerated ideas about China which is so "hot".

Such a transition should be done in a predictable environment. By "predictable", I mean predictable by the policymakers, not so much predictable by the speculators! I actually think that China itself should first demand more - e.g. higher taxes - from all the foreign (and domestic) companies that come there and the government should actually do more for their people! They're giving their capital - which is the work of the Chinese people - too cheaply. It probably sounds ridiculous if a pro-free-market advocate like I complains about the Chinese communist government that it is not sufficiently socialist on the economic issues, but well, this is what I do. :-)

When the situation in China is sufficiently cooled down so that the average expectation for the yuan motion is zero, it should become a freely floating currency. Floating the currency in the environment of high expectations helps primarily the speculators who buy the currency in time, but that's probably not the goal.

Let's return to America. OK, what do the deficits depend on?

The budget deficits after 2000 appeared because the US economy slowed down, and the deficits in 2003 and 2004 were affected by things like the war in Iraq. With an improved economy and improving situation in Iraq (hopefully), it may be expected that the budget deficit will decrease in 2005.

What about the trade gap? It is not right to assume that the healthier economy will reduce it too much. A growing economy means that the demand is strong, and the imports are strong as well. However it seems clear that the trade gap is large especially because it's still easy for the Americans to borrow money. As the interest rates grow - and hopefully there won't be anything that stops Greenspan to raise the basic interest rate to 3.5 - 4.0 % next year - they will reduce the consumption paid from the loans. This will naturally limit the trade gap. Higher interest rates may attract more investments, and the currency exchange rates may move closer to those when the US interest rates were high in the late 1990s - although this time, they necessarily won't be that high.

I am skeptical about the eurozone growth next year, and my estimate is 0% while the new members of the EU will have a moderately positive growth. The main reasons why the growth in the eurozone will not be positive are:

the jobs are gonna be moved to the Eastern Europe, and because most of the new countries will already be seen as comparably expensive, given the reduced quality of the workforce there, the jobs will be moved even more to the East. This will undermine the Western European job market and the domestic demand

the hedging contracts will evaporate throughout 2005 and the European exporters will see, without too much of the rosy glasses of hedging, what it means to be producing with a currency overvalued by 20-40 percent; we claim that a sustainable EUR/USD rate that allows growth everywhere is about $1.10 per euro

the inflexibility of the oversocialized European economy will take its toll

moreover, some new pressures suppressing the growth - such as the Kyoto protocol that will take effect in February - will start to act

Note about hedge funds and interest rates added later:

OK, let me finish with a judgement about the unbalanced situation on the market. It is mostly a fault of the small interest rates in the U.S. - in this sense, I apologize to Mr. Maestro - it is Alan Greenspan's fault. The very small interest rates have discouraged Americans from saving; the discouraged saving also reduces the intent to export; the small rates encourage them to borrow money and import. All these things support the semi-rational idea that the dollar should fall, and the dollar fall clearly does not solve anything. Americans still buy the same things and pay more for it; the foreign exporters get less for their exports, which makes them less able to import from America. The real inbalance is elsewhere, and the interest rates are a major reason.

There are lots of hedging funds and currency speculators around. These disgusting parasites are small replicas of George Soros who have decided to earn money simply by making bets that the dollar or something else will drop - and so far, the theory that this is the ultimate free lunch has worked for them. There should be no free lunches like that because a free lunch is something that makes economy inefficient - a free lunch is a socialist concept. The hedging pseudo-businessmen are not doing anything useful, and they receive a lot of money for this "work". Instead, they should be cleaning the toilets, for example, to be more useful for the society. They should be awarded for their excellent "work" they have done so far: for example, the Fed should raise the rates more than expected. The dollar would then recover much more rapidly than otherwise, and these stinky anti-dollar hedged bastards - which are worse than loop quantum gravity - should drown in their own blood, much like amoebas in a petri dish after we added acid. ;-)

The market should become much less predictable for the speculators - they should be much less able to predict the outcome. Because they're often able to predict, many people with poor moral standards become speculators, and many speculators around is certainly not good for the society as a whole. You know, in socialist Czechoslovakia, we used to have a lot of "wechselmen" who were buying the German mark from the German tourists for 10 crowns and selling it to the Czechs for 20 crowns while the communists claimed that the German mark was equal to 4 crowns (except that you could not buy it - but 4 crowns is what the Germans got in the bank). These people became pretty rich; in some sense, they were already building the market economy within socialism. That does not change anything about my opinion that these people are immoral, useless, and despicable, and the hedge funds are analogous.

My guess is that America can happily grow with up to 5 percent interest rates. It was only the period after the internet bubble burst when the people were so discouraged that they needed a smaller interest rate. Today, the USA should be able to return to the high interest rates. Greenspan has warned everyone sufficiently many times, and the next thing he should do is to act.

Friday, December 10, 2004
... /////

Gross was the first one I have watched. I highly recommend you to look at it! David explained how amazing their discovery was in the context of the 1960s.

It was a period of experimental supermacy and theoretical impotence. The experimentalists were making progress all the time while the theoreticians had no clue how to explain the obscure data about strongly interacting physics. Freeman Dyson declared in 1960:

The right theory of the strong force won't be found in the next 100 years.

Well, Dyson was only wrong by 87 years, Gross explains. He then sketches the renormalization, screening, anti-screening, quarks, Bjorken scaling, the competition between the S-matrix theory and field theory, the sum rules, the Landau pole and the Soviet claims that field theory was doomed, the pragmatic (calculational) character of American physicists, how quarks suddenly looked real, how the scaling suggested that there can be no interactions, how it seemed that interactions are always stronger at short distances, how they proved it with Coleman for spin below 1 theories, how QCD is beautiful, UV complete, and free of dimensionless parameters, how the asymptotic freedom improves gauge coupling unification, which is also helped by supersymmetry that many of us expect at the LHC, and so forth.

I've also listened to Frank Wilczek's talk - it is complementary in various respects - but someone else should describe it instead of me.

Thursday, December 09, 2004
... /////

The papers of David Gross and his students often turn out to be important, as the events in Stockholm will indicate tomorrow. But it is not the only reason why Ted Erler was invited to speak at our Duality Seminar about his recent paper with David Gross - a paper dealing with causality in string (field) theory.

Imagine that you work with the cubic string field theory. Three strings interact, and if you express the particular three strings in terms of fields localized at their centers of mass, you obtain a non-local interaction for your quantum field theory with infinitely many fields, of course. It's simply because the three centers of mass of your three interacting strings connected to the cubic vertex have no reason to coincide. In fact, it will also be non-local in time, not only in space, and such a non-locality in time (all derivatives of each field appear in the action) has disastrous consequences - the unbounded Hamiltonian is one of them.

The reporters asked Prescott, whom I need to introduce - he shares the economy Nobel prize - about the effects on economic growth if all people thought like Gross.

"It would be an unmitigated disaster."

Fair enough. The stability of the economy and humankind is based on the rule that the people like David Gross who don't have to follow the most simplified economic models are exceptional, and they should remain exceptional. The economy works because most people are subject to mechanisms that stimulate progress and production.

On the other hand, if every single human were able - and lucky enough - to contribute to the humankind as much as David Gross, the usual very-low-energy effective rules of economy, as Prescott knows them, would certainly break down. ;-)

This is a good point to say something related to Gross's statement - which may also be a news for many of our colleagues in economics:

The economists like Prescott may be intelligent ... but it's nothing compared to the scientists like Gross.

Indeed, one does not have to be a Nobel prize winner to say the statements that Prescott chose, like "it's totally OK to have budget deficits and the trade gap and it's OK if the currency rates fluctuate - in fact, it's better because I get much more of my Nobel prize." Come on, Mr. Prescott. These statements may be true, or false - and most likely, I would tend to agree that they're true and I would agree with Prescott's debunking of keynesianism - but these statements are mostly political proclamations - and biased guesses - i.e. statements without a too deep science behind them.

Even though I think that Prescott is a very reasonable and well-educated economist with good convictions based on common sense, I would expect a little bit more respect from Mr. Prescott to the people who are undoubtedly smarter than he is. ;-)

Well, these exchanges are just fun, of course. At the end, the Nobel prize winners agree about more or less everything. For example, they agree that the calls to boycott Israeli scientists are misled and contradict the principles necessary for progress in science.

A previous article on my blog about the background of the 2004 Nobel prize winners is here.

Although Jarah Evslin is an anarchist, his talk at the postdoc journal club was extremely organized and useful. His topic was

What is K-theory bad for and what it does not classify?

We immediately figured out a couple of possible answers - such as the hamburgers, and so forth. However, Jarah started and everything suddenly made much more sense. Jarah is a very mathematically skillful guy, but nevertheless, category theory is too hardcore even for him. Nevertheless, he wanted to solve similar tasks as category theory and classify various conserved brane charges and fluxes, and outlined the following sequence of mathematical objects:

Embeddings

Homotopy

Homology

K-homology

S-covariant K-homology

These sets are increasingly refined. Everytime you fall one step lower, your space only classifies a subspace of the upper one, and moreover makes some identifications (quotienting). Therefore, every new entry in the list above is a set which is smaller "by two contributions" than the previous one, given a natural definition of "smaller". Actually, every new entry is not quite obtained as a quotient of the subset of the previous one because it can "twist" the previous entry so that Z_2 cubed is replaced by Z_8, as an example below will indicate. Also, every new entry is "more conserved" - its charges (elements) are invariant under a broader class of physical processes than the elements of the previous classifying set.

Jarah has explained many examples in which the neighboring structures differ. For example, one-cycles on a genus g surface may be understood as embeddings. In that case, a D1-brane and a different D1-brane nearby cannot annihilate - this pair is distinguished in the structure called "embeddings". Then you may reduce the set of possible embeddings to homotopy; the first homotopy on the genus g surface is a non-Abelian group. Its abelianization gives you the homology; homology is a smaller group. I won't write anything else about the difference between embeddings and homotopy.

Instead, let's continue with the difference between homotopy and homology. Jarah has discussed various special cases - such as the branes on RP^7 x S^3. Homology gives you Z_2 for H_1, H_3, as well as H_5, and you might think that the natural group is Z_2 cubed - three independent numbers are added modulo 2. However, K-homology gives you a different answer. It shifts the Z_2's relatively to each other, so that Z_2 cubed is actually replaced by Z_8. This means that if you annihilate two 3-branes, instead of nothing you obtain a 1-brane, and so forth. He also defined K-theory, twisted K-theory, and gave several other examples.

We have had many discussions led by Jarah about the ability to refine K-theory in such a way that it is invariant under all dualities or satisfies similarly big constraints. Jarah's S-covariant K-theory is not invariant under T-duality, for example, simply because he classifies possible fluxes of the 3-form H, but he does not classify the possible topologies (geometry) even though these topologies may be T-dual to the H-fluxes. My feeling is that something that would classify all these conserved objects and respected all dualities would have to know - more or less - about the whole landscape, and therefore knowing this ultimately refined K-theory is almost equivalent to knowing the whole "theory of everything".

There are issues about these refined K-homologies being groups or just semigroups or nothing like that. It's intuitively clear that one expects a group structure for objects that can be thought of as small perturbations of a background. For example, K-theory should count all generalized D-branes - everything that contributes to the total energy/action by an amount proportional to 1/g_{string}. At weak coupling, that's much smaller than the tension/action of a nontrivial closed string background (e.g. NS5-branes) that goes like 1/g_{string}^2, and therefore it is natural that we get a structure of an Abelian group as K-theory. Once we add both NS-NS H-fluxes as well as R-R fluxes, it's not shocking to learn that the classifying set won't behave as a group. The condition of the objects being small perturbations of the same background does not hold anymore: similarly, we also don't expect the set of Calabi-Yau topologies to be a naturally definable group because we have no canonical way how to "add" topologies! ;-)

At any rate, Jarah's talk was very interesting and I am now very tired.

Wednesday, December 08, 2004
... /////

IBM has sold its PC production to a Chinese, state-controlled company called Lenovo (originally Legend) for 1.25 billion dollars. Half of the amount is paid immediately as cash, the other (smaller) half is paid by Lenovo's stocks. It's pretty amazing and it would have been hard to imagine 20 years ago.

IBM is a company with a long tradition. Incidentally, the Czechoslovak branch of IBM was nationalized (i.e. stolen by the communists) after the World War II, and it became a pathetic company called Kancelarske stroje, n.p. This company (the name means "Business Machines, National Company") was an excellent example of the technological inferiority of socialism: its products could have been compared to the Western products 15 years earlier. After the Velvet revolution, this gap immediately disappeared - and the very new technology penetrated through most levels of the Czechoslovak society.

In the early 1980s, IBM became the pioneer of the PC production - and in some sense, it was then viewed as a monopoly - maybe even more than Microsoft is viewed as having monopoly in the operating systems today. But capitalism is a very dynamical system. IBM made some errors - for example, a significant portion of its profit went exactly to Microsoft because Microsoft was more "clever" in making some deals (I am talking about the money from having MS-DOS on the IBM PCs).

Tuesday, December 07, 2004
... /////

Peter Woit is planning to create a permanent clipboard - or a macro - with a disclaimer that divides string theory into two pieces: a "useful toolkit" and a "colossal disaster". Because this macro is gonna be permanent, it may be useful to explain why it's inconsistent. This article will first quote Peter Woit who described his viewpoint on these issues in the "Comments" section under one of his articles, and then it will explain reality.

Peter Woit wrote:

I suppose I should write a macro so that whenever I write anything about the disastrous effect of string theory on particle physics it includes the disclaimer:

1. No, I'm not talking about the effect of string theory on mathematics, which, on the whole has been very positive.

2. No, I'm not talking about the idea of using string theory to get information about strongly coupled gauge theories, which has had some real successes.

3. Yes, I am talking about the idea that there is some fundamental 10 or 11 dimensional supersymmetric theory of extended objects which explains both quantum gravity and the standard model.

It's clearly point 3 that Krauss was referring to as a "colossal failure" and anyone who has read more than a few postings on this weblog would be well aware of points 1,2,and 3. The NYT article was not about whether string theory was successful as mathematics or whether it was promising as a way to solve QCD. It was very explicitly about the status of string theory as a unified theory and that is the issue to which my posting was addressed.

It was written by Dennis Overbye who is already an experienced string theory writer - and I must say that this article looks much better to me than the articles in the Time magazine or the Science magazine that appeared recently.

Overbye starts with a cute story from Aspen, Colorado, in 1984 - a story I've heard from John Schwarz, and it's good that someone finally used it in a popular article. The first public announcement of the Green-Schwarz anomaly cancellation - the discovery that started the first superstring revolution - was a theater play. John Schwarz entered the stage as a madman who was babbling about having discovered a theory capable to explain everything, and he was carried away by several men in white suites. People were laughing because they did not realize at that point that there would be at least 20 years in which the madman will be proved increasingly right by hundreds or maybe thousands of similar madmen.

Reynolds summarizes various recent scandals of the United Nations - the "oil-for-food" program; passivity regarding Darfur and Ukraine; pedophilia and rape done by the UN peacekeeping forces. And he explains that Havel is a hero on behalf on freedom who said that one must fight against the Evil, even if it requires the use of force. Finally, Reynolds analyzes how much corrupted the United Nations are and whether they will be more likely to be reformed under a leader who has a more significant moral authority.

The current Polish president (Alexander Kwaszniewski) and the former US president (Bill Clinton) are somtimes mentioned as possibilities, too. Well, I like the idea with Havel. The only possible disadvantage I see is Havel's health which has not been great.

Saturday, December 04, 2004
... /////

called "String theory gets real - sort of". The link above will only work at Harvard, so you will have to find the article elsewhere.

The article recalls the glorious moments 20 years ago, in 1984 - the year when the first superstring revolution started. In Aspen, Colorado, Michael Green and John Schwarz were working on the type I anomalies. Thunderstorm started and Michael Green said:

"We must be getting pretty close because God is trying to prevent us from finding the truth."

Unfortunately, this story is not from that article.

The text in the Science magazine says a lot of standard comments that string theory is our best hope to reconcile GR and QM, it requires extra dimensions, it can deal with the quantum foam, and so forth. It also explains how enthusiastic (or naive) people were right after the first revolution, and how much many people today dream about a more direct contact with experiments.

Wednesday, December 01, 2004
... /////

A rather large group of phenomenologists at Harvard, led by Nima Arkani-Hamed, spends one hour every Wednesday by analyzing the data from the LHC.

Today, they (or we) were making sure that the spins of the particles are what they should be. How can you tell that the Z boson - that has clearly been seen at the LHC, according to the graphs - is a spin one particle, as opposed to spin zero particle?

Well, the spin zero particles have a uniform angular distribution. The spin one particles, on the other hand, have different distributions as a function of the angles.

When the LHC creates a Z, it's almost never the "longitudinal" polarization parallel to the incoming momenta - it's because you must combine the opposite helicities from the two quarks contained in the proton. Consequently, the spin of the Z boson is always aligned with the quarks - their spin can never cancel. You can see the parabolic profile of the angular distribution even if you assume that 50% of the Z-bosons have one spin, and 50% have the other spin.

Analogously, we have also found some Z' (Z prime) particles, showing that they're spin one.

The next task was to identify some superpartners that the LHC has created for us - roughly 250 events. How can you say that the stop has spin zero? In fact, there are many differences between the bosons and the fermions.

The pair-production of the stop squarks has roughly 5 times larger cross section than for two top quarks - you may imagine that the fermions "repel" by the Pauli exclusion principle, and they correspondingly have a lower effective phase space.

Also, right above the production threshold, the cross section for producing the fermions goes like "beta" while the cross section for producing the bosons goes like "beta cubed", because of some extra derivative couplings for the boson.

The graphs showed relatively clearly that the stop squark was a spin 1/2 particle, and it decayed to the top quark plus a bino - which seems to be the lightest supersymmetric particle, as far as everyone sees. Some things are very easy to see - note that the LHC is producing roughly 6 jets per event, and their opening angle is roughly 10 degrees.

There have been some other graphs without much structure. They suck because it's hard to analyze what particles were exactly produced in these events.

Summary: the phenomenologists at Harvard are ahead of the experimentalists - I guess that the experimentalists won't be able to finish their first analyses of the LHC data earlier than 2007. ;-)

mostly sound like demotivating statements of bureaucrats - no doubt, in reality, there is a lot of outstanding scientists among them - who are always ready to kill every specific idea and replace it with a lot of neutrally sounding, boring cliches. They say, among other things

The plan is extraordinarily difficult.

It could threaten the funding of some other existing projects KQ, UH, PT, SJ.

Some sentences are so artificial, long, and boring that I don't even want to reproduce them here.

Concerning the second point above: it is exactly the whole point of the new vision of Bush - and any other vision of a similar kind - to re-evaluate the ideas what is important and attractive about the space exploration program and which projects should be completed and canceled. Some scientists just to believe that once their research of something has been accepted as legitimate research, it must be funded forever - and they would even like to hear that it is important forever. This is not how science within a finite society can work in the long run.

In fact, I would find it very useful if an influential politician who still knows how to be excited by something - like Bush - looked at other fields in science including particle physics. I think that the particle physicists - namely the experimentalists - are not using their resources efficiently either, and they're continuing to do many things that are almost guaranteed to lead nowhere, even though one could find many other projects that may have very clear and totally amazing outcomes. How much do we believe that Tevatron will bring us anything new and important? Of course that the world must preserve its family of skillful experimentalists even during the times in which the progress in the experiments is nearly frozen; but even such conservation should be done efficiently, and with a clear idea about the long-term goals.

Although I am a very theoretically oriented person, it's clear that I don't really care about KQ, UH, PT too much - and I care about SJ just a little bit. A human mission to Mars is something on a completely different level. Of course that such a mission is not just a matter of pure science. It is a way to realize the dreams of many of us - scientists as well as other people - dreams that we have had since we were little boys and girls.

A human mission to the Moon - or even to Mars - is something amazing and irresistable. And the idea of a more permanent base on the Moon or on Mars would represent new steps towards the dreams about a big future of our civilization. People were able to fly to the Moon in the 1960s and early 1970s, but it seems much more difficult for us today. What happened with us?

Let's list a few numbers:

The International Space Station's (ISS) total cost has been about 100 billion US dollars

The total budget for various telescopes etc. between 2000 and 2010 is about 5 billion dollars

The total cost of the Large Hadron Collider (LHC) is about 1.5 billion dollars

These basic numbers describing different projects should be listed for many other projects in science and space exploration, and there should exist a reasonable discussion within the scientific community and the policymakers which of these things are good investments and which of them are less good investments.

I may be a biased particle physicist, but the fact that we could have built 12 SSC supercolliders instead of the ISS is shocking. I have almost no idea what the ISS has been really good for - in what sense it was "better" or "more exciting" or "more scientifically interesting" compared to the first flight of Yuri Gagarin, for example. Note that it's nearly as expensive as the war in Iraq.

On the other hand, humans on Mars would be inspiring for the whole humankind.

Many people are scared by the dim future of the Hubble Space Telescope. You know, the funding in 2009 should be moved to the James Webb Space Telescope - a telescope that will focus on the infrared spectrum. My guess is that the Hubble will be viewed as giving us "nothing really new" much before 2009. Once it retires, it can be privatized or given to another country, and so forth. The progress must simply go on, and it is a completely wrong approach to assume that we will continue to work with the same technology forever. Of course that there must be completely new projects and new machines. And if there is a clear direction, it motivates the people to work on their specific tasks. And finally, it also encourages progress in the industry.

And let me make it sure that there exists no physical principle that will prevent the people from visiting Mars.

The report of the APS also says that the humans on Mars would also be counterproductive because they would contaminate the environment and prevent us from investigating the primary question - namely whether there has been life on Mars. I find such arguments ludicrous, and it's bad if such arguments are used to inhibit the progress in the space exploration program.

First of all, the humans could only "contaminate" the environment by the usual, terrestrial forms of life - and if such forms are found on Mars, everyone will believe that they were brought from the Earth anyway. If other forms of life - like different patterns replacing RNA/DNA - are seen on Mars, then the contamination by the terrestrial forms of life means no problems. Finally, if there's been any life on Mars, it does not seem that it could have been too impressive. I just think that Bush's vision of future life on Mars - something that we can initiate - is a much more exciting idea.

The possibility that there will be a usable base on Mars in this century is 100 times more intriguing than some hypothetical speculations that a robotic probe could find some specific organic compound on this planet. If we were able to create more permanent bases on the Moon or on Mars, it would give us new tools to investigate the Universe, and new hopes to expand our civilization to other places in the Cosmos.

I learned about this experiment from Wikipedia where it was uncritically described at various pages about the interpretation of quantum mechanics.

This Gentleman and colleague of ours has argued that he was able to falsify the Copenhagen interpretation as well as the Many Worlds Interpretation - WOW - and confirm an obscure interpretation - the so-called Transactional interpretation by an interference experiment of the type Welcher Weg (which way). This transactional interpretation, proposed by a physicist John Cramer, is based on signals being sent back and forth in time. :-)

Incidentally, an older article about the interpretation of quantum mechanics on this blog is here:

You know, category theory is the most abstract and "universal" part of rigorous mathematics, and it is also known as the (generalized) abstract nonsense. Actually the supporters of category theory don't view this name as an insult but rather as a cool compliment. Many of us have had a period in which the mathematical rigor was almost irresistable.

Category theory involves various theorems about sets, categories, functors, homomorphisms, and other abstract objects. Instead of saying "we perform an analogous procedure with a different kind of theory", category theorists give you a framework that translates vague words such as "analogous" into a mathematically rigorous structure.

This approach is meant to unify all of mathematics and all of rational thinking. You would think that the result must be very deep and hard to understand. But the actual results and tools of category theory are often closer to ordinary diagrams (combinatorial graphs) with arrows in between the objects - similar diagrams like those used by the people from the commercial sector in their PowerPoint presentations.

The mathematically oriented part of the string theory community is mostly excited by category theory. The so-called "derived categories (of coherent sheaves)" have been proposed as a generalization of K-theory to describe D-branes of various dimensions. Unlike K-theory that only knows about the allowed conserved charges of D-branes in various backgrounds, category theory should also know - and perhaps knows - something about their dynamics, for example the points in the moduli space at which the D-branes become (un)stable or (un)bound.

Wednesday, November 24, 2004
... /////

The messy elections in Ukraine look pretty serious. Just to make the situation clear:

There were two main presidential candidates. Both of them are called Viktor, but at most one of them can be the victor at the very end.

Viktor Yanukovich is a pro-authoritative, pro-Russian candidate, supported by the Eastern half of Ukraine as well as by Lukashenko and Putin (Byelorussia and Russia). Let me call him Viktor East because you may be confused by the similar names.

Viktor Yushchenko is a pro-Western, center-right candidate, who enjoys the support of the Western half of Ukraine, as well as the European Union and the United States of America. Let's call him Viktor West.

Exit polls indicated that Viktor West would win. Exit polls are not that important. Nearly official results indicated that Viktor East has won. However, the international observers claim that the polls were flawed. A lot of concrete accusations were raised and the EU and the US require a detailed audit of the polls.

Countries such as Czechia, Slovakia, Poland, Hungary, and the Baltic states are already members of the EU. Bulgaria and Romania could join the EU in a couple of years. The Baltic states are the only countries of the former Soviet Union that left the Commonwealth of Independent States. However it is pretty unlikely that Russia will join the EU in the foreseeable future. A real open question is Ukraine. Russia wants to interpret Ukraine as a "friendly region abroad" which is of course not quite compatible with Ukraine marching to the West. It's not shocking that Ukraine is the natural battleground for any new tension between Russia and the West.

Tuesday, November 23, 2004
... /////

The article starts by explaining who are cranks, and why many scientists turn on their e-mail filters to avoid all contacts with the crackpots. However, the article itself is then becoming increasingly entertaining, frustrating, or irritating, depending on your mood.

It explains that many parameters of the world seem to be adjusted in such a way that life is possible, and roughly speaking, the text proposes four main different explanations why it's so - and the first three explanations are related:

All of my left-wing anti-gasoline readers - and they probably constitute a majority of the readers - should consider their support for Billy Cottrell.

Billy Cottrell is a slightly eccentric :-) 23-year-old graduate student from Caltech who decided that the SUVs were evil, and therefore spray-painting (and possibly also torching) these SUVs is the right answer.

The total damages are about 2.3 million dollars and Cottrell has been threatened with up to 40 years in the prison. Well, it's not too surprising that he has probably agreed to become a police informant and his ecoterrorist friends have unfortunately stopped their support.

But why is it interesting? It's because Billy is described as a string theorist! The judge Gary Klausner, for example, mentioned that "string theory was an area of physics". Billy corrected him: "It's the area of physics." :-)

Of course, it's too bad that Billy has put himself into such problems, but he has some sympathies of mine, too. The main difference between Billy and the Kyoto protocol is that the damages made by Billy are 2.5 million, while those caused by the Kyoto protocol in the world will be 2.5 trillion - and the latter will be completely legal, unlike Billy's Molotov cocktails. :-) Moreover, the Kyoto is much less focused.

At any rate, I would like to discourage all of my other fellow string theorists from torching SUVs and other types of ecoterrorism.

The newest developments (I wrote them before, but blogger.com was frozen): Billy has been convicted on virtually all charges facing him, except for the most serious one that would imply at least 30 years in the prison. Without this particular charge, he is expected to spend roughly 5 years in the federal prison. His attorney wanted to argue that Billy had Asperger's syndrome, but it won't work, it seems.

I learned that he wrote a bachelor thesis about p-adic numbers in string theory at Chicago... I also learned about his research at Caltech which should be kept confidential, I think.

Saturday, November 20, 2004
... /////

Because the behavior of Linux and Mozilla is mostly unpredictable, I will try to write shorter articles.

Ian Swanson from Caltech has been visiting us. He has told us a lot of interesting stuff, and was also giving a special seminar yesterday (Friday) at 3:00 pm.

He used PowerPoint with a lot of sophisticated equations, tables, and some animations. His topic was String integrability and the AdS/CFT correspondence.

Let's describe Ian's talk and the current status of the post-BMN business. Because I am writing this for the second time, let me be shorter:

the industry of the pp-wave limit has transmuted into the spin chains and integrable systems

Ian Swanson et al. (which includes John Schwarz, but also Jonathan Heckman who is now at Harvard) studied the physics of strings beyond the pp-wave - which means that AdS5 x S5 is described as the pp-wave deformed by some 1/R^2 corrections

the gauge theory side of the calculation more or less reduces to the spin chains and other tools of integrable systems

the string theoretical side is described by the Green-Schwarz string that, at least classically, becomes the supercoset SU(2,2|4) / ( SO(5) x SO(4,1) ), if I remember well - and as long as you forget about stringy loops, the ghosts (like Berkovits' pure spinors) are not necessary

the integrable structure on both sides agree, even though it is not manifest

most of the calculations are done at the leading order of the 1/N expansion (or the J^2/N expansion), and the stringy loop corrections are more or less open questions

the results are still expanded in lambda'=lambda/J^2, and in 1/J

the gauge theory (spin chains) agrees with the string (supercoset) at the one-loop and the two-loop level

there is a discrepancy at the three-loop level, and Ian says that it is believed that the problem is a subtlety neglected by the spin chain models

many states are combined into various multiplets, and there is indirect evidence of the existence of an infinite number of conserved charges that make up the integrable structure

It is a fulltext search engine through all scientific articles, including all articles from www.arxiv.org (the PDF files are those that are linked), and it knows about the number of citations. The server lists the article with the given query and it prefers the cited articles.

Wednesday, November 17, 2004
... /////

Last time when I commented all the articles, we were impressed how interesting and serious they were. Tonight it's slightly easier to describe all the hep-th papers on the web, but some of them still look interesting:

This paper by Matthew Headrick and Joris Raeymaekers is obviously interesting. Consider the nonsupersymmetric orbifold of type II string theory - Adams-Polchinski-Silverstein (APS) type of orbifold - on C/Z_n for large n. You know that there are many tachyons in the twisted sectors. For large n, it makes sense to T-dualize around the angular direction of C/Z_n. You get some SUGRA solution. Well, many people have definitely looked at the orbifold in this way, using T-duality. But Matt and Joris finally consider the obviously interesting limit in which n is sent to infinity, but you keep n times alpha' fixed. It's some kind of zero slope limit, but the "lightest" tachyons (=closest to being massless) whose squared masses are comparable to (-1/alpha' n) survive this limit because these squared masses are exactly inverse to the quantity that is kept fixed.

Note that the tachyons come from twisted sectors. By interpreting the angle as a circle, they're winding strings. It means that in the T-dual picture, they are momentum modes of a field in the dual string theory which is effectively supergravity. Finally, the present authors calculate some interactions of the momentum modes in supergravity - which exist off-shell - and they show that they agree with the couplings of the different tachyons calculated from the CFT - which only exist on-shell. That's very interesting. The main thing I worry about is that the result is perhaps not too unexpected because instead of the orbifold, one might work directly with the "limiting CFT" on the thin cone and its T-dual.

This author constructs some new solutions of the modified Ricci-flatness equations, something that is necessary for a CFT to be well-defined. You know that Ricci flatness is the right equation of motion only if you have no fluxes and if the dilaton is constant. If the dilaton is not constant, the Ricci tensor is nonzero - Einstein's equations get a source. He or she does not quite want to talk about a non-constant dilaton. Instead, he or she focuses on another generalization of the CFT and Ricci flatness - namely a CFT with an extra complex field that has an "anomalous dimension". My understanding is that it's just a matter of notation whether you say that a field has an "anomalous dimension", or whether you redefine it by a function of the dilaton, and you allow the dilaton to vary. If my understanding is correct, Nitta has effectively found new solutions of the combined Einstein's equations with some dilaton-gradient source. These solutions have either a U(N) isometry, or an O(N) isometry. It's because the coordinates of his or her manifolds are explicitly written using U(N) or O(N) covariant coordinates, and the metric only depends on the quadratic invariants. Some of these solutions can be interpreted as generalizations or deformations of the Ricci-flat metric of the conifold with an extra linear dilaton - at least that's my impression.

We often say that the maximally supersymmetric Yang-Mills theory in four dimensions is "finite" because of powerful supersymmetric cancellations. Well, what is exactly is finite? Clearly, there are operators with anomalous dimensions that must be regulated and that are cutoff-dependent, and so forth. So it's not everything that is finite. However, the effective action is something that should be finite - it sort of computes the correlators of the elementary fields in which the divergences are supposed to cancel between the bosons and fermions. In this paper, these two guys try to prove the finiteness of the N=4 effective action in the N=1 superspace language. The effective action of N=4 can be written in this form, due to the Slavnov-Taylor identity, as long as we allow the superfields to be "dressed". They must go through some un-controversial steps to show that the R-symmetry anomaly cancels due to the N=2 supersymmetry, and they re-check that the one-loop beta-function vanishes. Nevertheless, the final result is that once you express the effective action of the N=4 gauge theory in terms of the dressed fields, all the terms become independent of the UV cutoff, and the effective theory is therefore finite.

OK, there was a Lorentz violating paper last time, too, and many comments may be repeated. I still don't understand the motivation behind these models. The space of possible non-relativistic non-stringy quantum field theories is huge. I don't really feel what constrains it. For relativistic theories, we may label all fields by their dimension - which is their dimension with respect to space as well as time. However, for non-relativistic theories, we must introduce separate spatial and temporal dimensional analyses, and I don't think that we can really distinguish "renormalizable" theories from "non-renormalizable" theories. Of course, this can be done if we write down a non-relativistic theory as a deformation of a relativistic theory, and this is what this groups does, too. Nevertheless the number of new terms, once you allow the Lorentz symmetry to be broken, is again huge. Moreover, I think that the lessons of 1905 are serious lessons, and breaking the Lorentz invariance explicitly should also be accompanied by breaking of the rotational invariance, and I see no reasons to do so. Let's stop criticism for a while.

What theory do they consider? Take the usual Maxwell action in four dimensions, and imagine that you decide to deform it in some way, by adding another action. What is the other action you know for a U(1) gauge field? Well, the Chern-Simons action. There is a problem: the usual Chern-Simons term only exists in three dimensions. However, that's not a problem for those who don't care about the Lorentz invariance. Just multiply the Chern-Simons 3-form with a general vector, i.e. a 1-form, to get a 4-form, and you can integrate the product over the spacetime. The vector picks a priviliged direction which is OK with you. Because the Chern-Simons action has an epsilon in it, you will break not only the Lorentz symmetry but also the CPT symmetry - which can happen once the Lorentz symmetry is gone. To make the things even more confusing, add an external current J that couples to the gauge field via the J.A term.

That was too natural so far. Let's make something more fancy. Reduce this four-dimensional Lorentz invariant theory to three spacetime dimensions (dimensional reduction). Moreover, don't reduce it along the priviliged vector discussed previously, but along a more general vector. In this case, the three-dimensional Lorentz symmetry will still be violated. If you write down some terms, you will discover mass terms of various types. Just do it and derive the equations of motion and solve them and draw several graphs. And don't forget to be excited that the results pick a priviliged reference frame (even though you know that it was your starting point). It's probably a good feature to violate the Lorentz symmetry.

Finally, let me admit that I am totally lost. I have no idea why they're doing what they're doing, whether it should be a physically realistic model or a mathematically interesting one: I just don't see the meaning of it all. This type of activity is what most of us would be doing today if we had no string theory. Combining random terms that apparently follow no deeper or organizational principles - terms extracted from an infinite chaotic ocean of arbitrary terms and their combinations - terms that are much more ugly and unjustified than the theories that are known to work. Sorry for being so skeptical; I might simply be dumb.

These colleagues first repeat a lot of the commercials about "Causal Dynamical Triangulations" that they've already written in many previous papers. The starting points are very obvious and sort of naive: try to define the path integral of quantum gravity in a discretized form. (It's like spin foams in loop quantum gravity, but you don't necessarily require that the details will agree.) OK, so how can you discretize a geometry? You triangulate it into simplices, and you imagine that every simplex has a region of flat Minkowski spacetime in it.

(That's not like loop quantum gravity - the latter assumes that there is no geometry "inside" the spin foam simplices - the geometry is concentrated at the singular points and edges of the spin foam.)

Then you write down the Einstein-Hilbert action many times and you emphasize that it is discretized. There are many other differences from loop quantum gravity: while the minimal positive distance in loop quantum gravity is sort of Planckian, in the present case they want to send the size of the simplices to zero and the regulator should be unphysical. Of course that if you do it, you formally get quantized general relativity with all of its problems: as soon as the resolution becomes strongly subPlanckian, the fluctuation of the metric tensor becomes large. The path integral will be dominated by heavily fluctuating configurations where the topology changes a lot and where the causal relations are totally obscured - and the results of these path integrals will be non-renormalizably divergent - at least if you expand them perturbatively. But this is simply what a correct, authentic quantization of pure gravity gives you.

These authors are doing something different in one essential aspect. They don't want to sum over all configurations, all metrics - the objects that you encounter in the foamy GR path integral above. They don't do it because they sort of know that pure GR at subPlanckian distances is rubbish. Instead, they truncate the path integral to contain "nice and smooth" configurations only. The allowed configurations they include must be not only nice, but they must have the trivial causal diagram as well as a fixed topology - namely S3 x R in their main example. Well, if you restrict your path integral to configurations that look nice, it's not surprising that your final pictures will look nice and similar to flat space, too. But it by no means implies that you have found a physical theory.

Any path integral that more or less works simply must be dominated by configurations that are non-differentiable almost everywhere, by the very nature of functional integration and by the uncertainty principle. One can often show that the path integral localizes, but that's just a result of theorems and calculations. One cannot define the path integral to include smooth and causal histories only. Such a definition simply violates the uncertainty principle as well as locality, if you make some global constraints on the way how your 3-geometry can look like. Consequently, it also violates general covariance, and you won't decouple the unphysical polarizations. If you also make global constraints about the allowed shapes as functions of time that cannot be derived from local constraints, you will also violate unitarity.

As far as I know, none of these "discrete gravity" people ever asked the question whether these theories are physical, unitary, and so forth. In fact, the subset of the "discrete gravity" people called the "loop quantum gravity" people declares quite openly that they don't care about unitarity at all. Unitarity is actually one of their enemies and they claim that it follows from time-translation symmetry, which is of course a misunderstanding of total basics of physics: unitarity is about hermiticity of the Hamiltonian, if one exists, while time-translation symmetry is about its time-independence. Unitarity is one of the concepts that must be destroyed by the revolution in physics that they've been planning for quite some time. ;-) They're just not getting that unitarity is about the probabilities being non-negative numbers that sum up to one, and that this rule must work in any context in quantum physics. I am afraid that the rest of the "discrete gravity" people does not bother to check these elementary physics questions either. That may be a good point to stop criticism because everyone knows it anyway that I don't believe that this line of research will lead to any usable new physics because it simply neglects some totally essential features of quantum physics.

At any rate, they show that these strange rules of the game admit some big-bang big-crunch cosmological solution described by some collective coordinates (a nice picture animates in front of your eyes), and they construct or propose a wave function of the Universe that depends on the observable representing the "3-volume of the Universe".